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Dive into the research topics where Sarah Abdalla Ahmed is active.

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Featured researches published by Sarah Abdalla Ahmed.


Fungal Diversity | 2014

Proposed nomenclature for Pseudallescheria, Scedosporium and related genera

Michaela Lackner; G. Sybren de Hoog; Liyue Yang; Leandro F. Moreno; Sarah Abdalla Ahmed; Fritz Andreas; Josef Kaltseis; Markus Nagl; Cornelia Lass-Flörl; Brigitte Risslegger; Günter Rambach; Cornelia Speth; Vincent Robert; Walter Buzina; Sharon C.-A. Chen; Jean-Philippe Bouchara; José F. Cano-Lira; Josep Guarro; Josepa Gené; Fabiola Fernández Silva; Rosa M. T. Haido; Gerhard Haase; Vladimír Havlíček; Dea Garcia-Hermoso; Jacques F. Meis; Ferry Hagen; Martin Kirchmair; Johannes Rainer; Katharina Schwabenbauer; Mirjam Zoderer

As a result of fundamental changes in the International Code of Nomenclature on the use of separate names for sexual and asexual stages of fungi, generic names of many groups should be reconsidered. Members of the ECMM/ISHAM working group on Pseudallescheria/Scedosporium infections herein advocate a novel nomenclature for genera and species in Pseudallescheria, Scedosporium and allied taxa. The generic names Parascedosporium, Lomentospora, Petriella, Petriellopsis, and Scedosporium are proposed for a lineage within Microascaceae with mostly Scedosporium anamorphs producing slimy, annellidic conidia. Considering that Scedosporium has priority over Pseudallescheria and that Scedosporium prolificans is phylogenetically distinct from the other Scedosporium species, some name changes are proposed. Pseudallescheria minutispora and Petriellidium desertorum are renamed as Scedosporium minutisporum and S. desertorum, respectively. Scedosporium prolificans is renamed as Lomentospora prolificans.


Mycoses | 2015

Spectrum of Fusarium infections in tropical dermatology evidenced by multilocus sequencing typing diagnostics.

Anne D. van Diepeningen; Peiying Feng; Sarah Abdalla Ahmed; M. Sudhadham; Sumanas Bunyaratavej; G. Sybren de Hoog

Fusarium species are emerging causative agents of superficial, cutaneous and systemic human infections. In a study of the prevalence and genetic diversity of 464 fungal isolates from a dermatological ward in Thailand, 44 strains (9.5%) proved to belong to the genus Fusarium. Species identification was based on sequencing a portion of translation elongation factor 1‐alpha (tef1‐α), rDNA internal transcribed spacer and RNA‐dependent polymerase subunit II (rpb2). Our results revealed that 37 isolates (84%) belonged to the Fusarium solani species complex (FSSC), one strain matched with Fusarium oxysporum (FOSC) complex 33, while six others belonged to the Fusarium incarnatum‐equiseti species complex. Within the FSSC two predominant clusters represented Fusarium falciforme and recently described F. keratoplasticum. No gender differences in susceptibility to Fusarium were noted, but infections on the right side of the body prevailed. Eighty‐nine per cent of the Fusarium isolates were involved in onychomycosis, while the remaining ones caused paronychia or severe tinea pedis. Comparing literature data, superficial infections by FSSC appear to be prevalent in Asia and Latin America, whereas FOSC is more common in Europe. The available data suggest that Fusarium is a common opportunistic human pathogens in tropical areas and has significant genetic variation worldwide.


Journal of Clinical Microbiology | 2012

Pleurostomophora ochracea, a novel agent of human eumycetoma with yellow grains

Najwa A. Mhmoud; Sarah Abdalla Ahmed; Ahmed H. Fahal; G. Sybren de Hoog; A.H.G. Gerrits van den Ende; Wendy W. J. van de Sande

ABSTRACT The first yellow-grain fungal mycetoma, in a 60-year-old man from Central Sudan, is reported. Morphological and phylogenetic analysis of the ribosomal small subunit (SSU), large subunit (LSU), internal transcribed spacer (ITS), β-tubulin (BT2), actin (ACT1), and elongation factor (TEF1) genes revealed that the isolate deviated from any known agent of mycetoma; it clustered in the genus Pleurostoma (anamorph genus, Pleurostomophora) in the order Calosphaeriales. The novel species, here named Pleurostomophora ochracea, is characterized by phenotypic features. The species proved to be highly susceptible to itraconazole, ketoconazole, posaconazole, and voriconazole, but not to fluconazole. The fungus was inhibited by caspofungin at 8 μg/ml, while no inhibition was found with 5-flucytosine (MIC > 64 μg/ml). Compared to other members of the genus Pleurostomophora, P. ochracea is slow growing, with a relatively high optimum growth temperature (36 to 37°C). This is the first case of a yellow-grain fungal mycetoma; yellow grains are otherwise of bacterial nature. Our case emphasizes that identification of mycetoma agents by the color of the grain only is not sufficient and may lead to inappropriate therapy.


PLOS Neglected Tropical Diseases | 2014

Rapid Identification of Black Grain Eumycetoma Causative Agents Using Rolling Circle Amplification

Sarah Abdalla Ahmed; Bert Gerrits van den Ende; Ahmed H. Fahal; Wendy W. J. van de Sande; G.S. de Hoog

Accurate identification of mycetoma causative agent is a priority for treatment. However, current identification tools are far from being satisfactory for both reliable diagnosis and epidemiological investigations. A rapid, simple, and highly efficient molecular based method for identification of agents of black grain eumycetoma is introduced, aiming to improve diagnostic in endemic areas. Rolling Circle Amplification (RCA) uses species-specific padlock probes and isothermal DNA amplification. The tests were based on ITS sequences and developed for Falciformispora senegalensis, F. tompkinsii, Madurella fahalii, M. mycetomatis, M. pseudomycetomatis, M. tropicana, Medicopsis romeroi, and Trematosphaeria grisea. With the isothermal RCA assay, 62 isolates were successfully identified with 100% specificity and no cross reactivity or false results. The main advantage of this technique is the low-cost, high specificity, and simplicity. In addition, it is highly reproducible and can be performed within a single day.


PLOS Neglected Tropical Diseases | 2014

Madurella mycetomatis is highly susceptible to ravuconazole

Sarah Abdalla Ahmed; Wendy Kloezen; Frederick Duncanson; Ed E. Zijlstra; G. Sybren de Hoog; Ahmed H. Fahal; Wendy W. J. van de Sande

The current treatment of eumycetoma utilizing ketoconazole is unsatisfactory because of high recurrence rates, which often leads to complications and unnecessary amputations, and its comparatively high cost in endemic areas. Hence, an effective and affordable drug is required to improve therapeutic outcome. E1224 is a potent orally available, broad-spectrum triazole currently being developed for the treatment of Chagas disease. E1224 is a prodrug that is rapidly converted to ravuconazole. Plasma levels of E1224 are low and transient, and its therapeutically active moiety, ravuconazole is therapeutically active. In the present study, the in vitro activity of ravuconazole against Madurella mycetomatis, the most common etiologic agent of eumycetoma, was evaluated and compared to that of ketoconazole and itraconazole. Ravuconazole showed excellent activity with MICs ranging between ≤0.002 and 0.031 µg/ml, which were significantly lower than the MICs reported for ketoconazole and itraconazole. On the basis of our findings, E1224 with its resultant active moiety, ravuconazole, could be an effective and affordable therapeutic option for the treatment of eumycetoma.


Medical Mycology | 2015

In vitro antifungal susceptibility of coelomycete agents of black grain eumycetoma to eight antifungals.

Sarah Abdalla Ahmed; G. Sybren de Hoog; David A. Stevens; Ahmed H. Fahal; Wendy W. J. van de Sande

Fungal mycetoma (eumycetoma) represents one of the most difficult infections to appropriately manage. The current recommended treatment is based on extensive surgical debridement combined with prolonged antifungal therapy with ketoconazole or itraconazole. Despite the different phylogenetic positions of black-grain eumycetoma species, they are all treated with the same antifungal agents. The in vitro antifungal susceptibility of coelomycetous eumycetoma agents in the order of Pleosporales presently is largely unknown. Here we determined the in vitro activity of eight antifungal agents against seven species causing human eumycetoma using the Sensititre YeastOne method. High minimum inhibitory concentrations (MICs) were found with fluconazole, caspofungin, flucytosine, and amphotericin B. Voriconazole and posaconazole were found to be active against all species tested. Of the species included in the investigation, MICs of Medicopsis romeroi differed from the rest of the mycetoma causative agents belonging to the order of the Pleosporales. We found significantly lower MICs for amphotericin B and significantly higher MICs for fluconazole, ketoconazole, and itraconazole against this species. Our results emphasised that identification of black grain mycetoma agent is important as well as performing susceptibility testing before starting of antifungal treatment.


Journal of Clinical Microbiology | 2015

Application of Isothermal Amplification Techniques for Identification of Madurella mycetomatis, the Prevalent Agent of Human Mycetoma

Sarah Abdalla Ahmed; Wendy W. J. van de Sande; Marie Desnos-Ollivier; Ahmed H. Fahal; Najwa A. Mhmoud; G.S. de Hoog

ABSTRACT Appropriate diagnosis and treatment of eumycetoma may vary significantly depending on the causative agent. To date, the most common fungus causing mycetoma worldwide is Madurella mycetomatis. This species fails to express any recognizable morphological characteristics, and reliable identification can therefore only be achieved with the application of molecular techniques. Recombinase polymerase amplification (RPA) and loop-mediated isothermal amplification (LAMP) are proposed as alternatives to phenotypic methods. Species-specific primers were developed to target the ribosomal DNA (rDNA) internal transcribed spacer (ITS) region of M. mycetomatis. Both isothermal amplification techniques showed high specificity and sufficient sensitivity to amplify fungal DNA and proved to be appropriate for detection of M. mycetomatis. Diagnostic performance of the techniques was assessed in comparison to conventional PCR using biopsy specimens from eumycetoma patients. RPA is reliable and easy to operate and has the potential to be implemented in areas where mycetoma is endemic. The techniques may be expanded to detect fungal DNA from environmental samples.


Antimicrobial Agents and Chemotherapy | 2012

In Vitro Activities of Nine Antifungal Drugs against 81 Phialophora and Cyphellophora Isolates

Peiying Feng; M. Javad Najafzadeh; Jiufeng Sun; Sarah Abdalla Ahmed; Liyan Xi; G. Sybren de Hoog; Wei Lai; Chun Lu; Corné H. W. Klaassen; Jacques F. Meis

ABSTRACT Cyphellophora guyanensis (n = 15), other Cyphellophora species (n = 11), Phialophora europaea (n = 43), and other Phialophora species (n = 12) were tested in vitro against nine antifungal drugs. The MIC90s across all of the strains (n = 81) were, in increasing order, as follows: posaconazole, 0.063 μg/ml; itraconazole, 0.5 μg/ml; voriconazole, 1 μg/ml; micafungin, 1 μg/ml; terbinafine, 2 μg/ml; isavuconazole, 4 μg/ml; caspofungin, 4 μg/ml; fluconazole, 8 μg/ml; amphotericin B, 16 μg/ml.


Fungal Diversity | 2016

Chaetomium-like fungi causing opportunistic infections in humans: a possible role for extremotolerance

Sarah Abdalla Ahmed; Ziauddin Khan; Xue wei Wang; Tarek A. A. Moussa; Hassan S. Al-Zahrani; Omar A. Almaghrabi; Deanna A. Sutton; Suhail Ahmad; Johannes Z. Groenewald; Ana Alastruey-Izquierdo; Anne D. van Diepeningen; S.B.J. Menken; Mohammad Javad Najafzadeh; Pedro W. Crous; Oliver A. Cornely; Axel Hamprecht; Maria J.G.T. Vehreschild; Anupma Jyoti Kindo; G. Sybren de Hoog

Members of the family Chaetomiaceae are ubiquitous ascosporulating fungi commonly, which reside in soil enriched with manure or cellulosic materials. Their role as human pathogens is largely ignored. However, the ability of some species to grow at high temperature enables them to play an important role as opportunistic pathogens. The family contains several genera and species that have never been reported to cause human infection. Hereby, three new species are described; two belong to the genus Subramaniula and one represents a Chaetomium species. Subramaniula asteroides was isolated from various sources including eye and skin infections as well as from the natural environment, and S. obscura was isolated from a toe infection. Chaetomium anamorphosum was isolated from a kidney transplant patient suffering from fungal peritonitis. All species described were previously misidentified as Papulaspora spp. due to the formation of cellular clumps or bulbil-like structures, which are characteristic of Papulaspora. The isolates failed to form sexual fruit bodies and ascospores remained absent, which is an unusual feature for the generally ascosporulating genera Chaetomium and Subramaniula; minute conidia from phialides were sometimes observed.


Journal of Clinical Microbiology | 2015

Phaeohyphomycosis Caused by a Novel Species, Pseudochaetosphaeronema martinelli

Sarah Abdalla Ahmed; Nicole Desbois; David M. Quist; Charline Miossec; Carlos Atoche; Alexandro Bonifaz; G. Sybren de Hoog

ABSTRACT Among the opportunistic mycoses that are emerging in patients with immunosuppression or severe underlying illness, many isolates lack of characteristic sporulation and until recently could not be identified. Clinical signs are mostly nonspecific and therefore such infections have often been disregarded. In the present paper we describe a novel, nonsporulating fungal species causing subcutaneous phaeohyphomycosis in two patients of different origin. One is a 73-year-old female from Martinique who suffered from rheumatoid arthritis, while the other case concerns a 72-year-old male from Mexico who had a history of type 2 diabetes mellitus. Sequencing of the partial ribosomal operon revealed that in both cases a member of the order Pleosporales was concerned which could not be affiliated to any family within this order. Multilocus analysis revealed that the fungus was related to another, unaffiliated agent of human mycetoma, Pseudochaetosphaeronema larense, and therefore the name Pseudochaetosphaeronema martinelli was introduced.

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G.S. de Hoog

Centraalbureau voor Schimmelcultures

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Jacques F. Meis

Radboud University Nijmegen

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Anne D. van Diepeningen

Royal Netherlands Academy of Arts and Sciences

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Bert Gerrits van den Ende

Royal Netherlands Academy of Arts and Sciences

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Ed E. Zijlstra

Royal Tropical Institute

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Wendy Kloezen

Erasmus University Rotterdam

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